Scott MacPhee is certainly not the only wargamer to paint his Roman Montefortino and Coolus helmets in a nicy shiny bronze.

That's certainly not something I'd disagree with. All the evidence suggests that Roman soldiers were all about 'Bling'. One needs to only think of the intricately decorated belts and scabbards to realize that. I'd just suggest that shiny bronze need not be the only color. Many bronze Roman helmets have traces of tinning. So how about some shiny tinned helmets in future? Might make for faster painting too, using the same colors for armor and helmet!

Below's an example of a Montefortino type C from Nijmegen, dated to the very late 1st century BC / early 1st century AD with clear traces of tinning still visible.